MEMBERS OF THE BOARD OF TUTORS

Kleckner, Nancy, Ph.D.

Behavior of chromosomes in bacteria and yeast: We are interested in two aspects of chromosome metabolism: recombination and chromosome segregation. We analyze these processes in both prokaryotes (E. coli) and eukaryotes (yeast S. cerevisiae) using genetic, biochemical, and cytological methods.1. Transposition in E. coli. The bacterial transposon Tn10 moves by a series of specific DNA breaking and joining events which require a Tn10-encoded transposase protein and accessory host proteins, IHF and HU. We wish to understand the precise nature andorder of reaction steps, the types of DNA/protein complexes involved, the way in which the transposon ends find one another, the mechanistic role of host factors, the importance of DNA topology, and the functional organization of transposase protein.2. Meiosis in S. cerevisiae. During meiosis, homologous chromosomes recognize one another ("pair") and engage in recombination prior to, and as a prerequisite for, their segregation at the first meiotic division. We are examining the pairing and recombinaion processes, their control, and their integration with the cell cycle during meiosis in yeast. Genetic, cytological and biochemical approaches are used.3. Control of replication initiation in bacteria. We are investigating the regulation of replication initiation in E. coli. We are analyzing the role of recently discovered negative regulatory protein, SeqA, which works in concert with DNA adenine methylaion at specific sites in the replication origin. We are also searching for new factors which may participate in replication timing and in maintaining coordination between initiation and cell division. - Bürner, G.V., Kleckner, N. and Hunter, N. (2004) Crossover/noncrossover differentiation, synaptonemal complex formation and regulatory surveillance at the leptotene/zygotene transition of meiosis. Cell 117, 29-45.